It is an understatement to say that one can lead a happy and fulfilled life without supernatural religion.
Why is God considered an explanation for anything? It’s not - it’s a failure to explain, a shrug of the shoulders, an ‘I dunno’ dressed up in spirituality and ritual. If someone credited something to God, generally what it means is that they haven’t a clue, so they’re attributing it to an unreachable, unknowable sky-fairy. Ask for an explanation of where that bloke came from, and odds are you’ll get a vague, pseudo-philosophical reply about having always existed, or being outside nature. Which, of course, explains nothing.
I’m just going to make this distinction one more time.
I believe there is not a god.
The placement of the word “not” before god, rather than believe, indicates that there is a belief against the existence of a god. In the same way that you might say “I believe my mother is not at the store.” You have strong evidence to support that she is at the doctor, possibly, which in turn serves as evidence that she is not at the store.
I do not believe there is a god.
By placing “not” before believe, instead of god, you indicate that there is an absence of belief, rather than a firm belief in the absence.